Riding lawn mower



FIG. 1 is a front view of a riding lawn mower showing my new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is an enlarged left side view of a portion thereof taken along lines 8-8 shown in FIG. 3.

The broken line showings of FIGS. 1-8 are environmental only and not part of the claimed design. 

CLAIM The ornamental design for a riding lawn mower, as shown and described. 